Kahn, congratulations on owning a fine gun and piece of history as well. I believe the gun is a 1950 Model 409 Bis. It is an Anson & Deeley action whose patent goes back to Westley Richards Co. in the 1800s; Beretta began producing this gun in 1926 and continued (with variations in features and finish) until the 42x series was introduced in 1963. Your gun was most likely imported by Godfrey & Co. NYC.
There is a group of Beretta SxS enthusiasts you might like to hook up with...we publish a newsletter that would tell you a lot about the old guns; there's no cost. Let me know: jim.bode@frontier.com